Gut-Brain Axis: a new revolution to understand the pathogenesis of autism and other severe neurological diseases

The gut–brain axis (GBA) is a complex communication network interfacing the gut and the brain of a single individual. The central (CNS) and enteric (ENS) nervous systems are, of course, communicating; however, other pathways are involved in GBA, among which are immune activation, intestinal barrier function, and entero- endocrine signaling. All these communication lines are bidirectional and involve neuro-immuno-endocrine mediators. The reason for the development of such a complex network is to maintain gastrointestinal homeostasis keeping in mind its links with cognitive and affective functions. Recently, the role of enteric flora, or microbiota, has been recognized as a part of the gut–brain axis. The gut microbiota can modulate brain function, forming a crucial link in the bidirectional interactions between the intestine and the nervous system.